原创 Handy troubleshooting tip: Bang on it!

Here's a picture of my oscilloscope: a 1966 15Mhz Tektronix Type 422.

Vintage 1966 15Mhz Tektronix Type 422

When I bought my oscilloscope for twenty dollars, it was dead. Someone had tried to stick ten pounds of fuse into a one-pound fuse holder and subsequently broke the fuse holder. I replaced the fuse holder with a non-standard fuse holder and a fuse of the recommended type and rating, thus returning the instrument to a functioning capacity.

Vintage scope with new fuse holder.

Now, the Tektronix Type 422 Oscilloscope is a fine instrument of quality manufacture, but I would like to try some of those new features they've come up with since the moon landing—features like 200MHz bandwidth, 1GS/s, 4 analogue channels, 16 digital channels, automated measurements, and FFT analysis that are provided by the Tektronix MSO2024B digital oscilloscope that is the prize of this contest, so I'm going to tell you this story.

One day, I received a message from manufacturing that they had an instrument that was dead and that they required the assistance of my superior technical skills and extensive engineering knowledge acquired through advanced education and years of experience. So, I put on my anti-static smock and my anti-static shoe straps and grabbed my trusty DVM with the very pointy probes and headed down to manufacturing to render said assistance.

Upon arriving in manufacturing and being shown the instrument, I asked the manufacturing engineer what was wrong with the device. He replied, "If I knew that, I would not require the assistance of your superior technical skills and extensive engineering knowledge acquired through advanced education and years of experience."

So, I asked, "Well what's the problem?" He said, "It's dead." I said, "Well, what did you try?" He said, "I replaced all the boards with known good boards and the power supply with a known good power supply and it is still dead."

He spilled the beans. I knew he would crack under my relentless questioning.

As I sat down by the instrument, I bumped the table, which caused the screen to blink. So I banged on the table, causing the screen to blink again. I continued to bang on the table making the screen blink much to the amusement of the technicians working behind me. I did not care because I had a nibble and I was going to play it out before I got lost in the labyrinth of the innards of the device.

Handy troubleshooting technique.

After several minutes of judicious banging, the screen came up and stayed on. I heard from behind me someone guffaw, "He's got it working," followed by laughter from the peanut gallery. I then took my pen and poked at the cables in the device until I found one that caused the screen to malfunction. I shut down the instrument and removed the cable.

Then, using my superior technical skills and extensive engineering knowledge acquired through advanced education and years of experience, and using my trusty DVM with the very pointy probes, I determined that the cable was indeed defective; knowledge of which I imparted on the manufacturing engineer, thus proving the old adage that it is not enough to think outside the box. Sometimes you have to bang on the side.

So please kindly consider my submission, though it is as badly stitched together as Frankenstein's monster (if Dr. Frankenstein had used duct tape) and send me that fancy new Tektronix MSO2024B digital oscilloscope that is the prize of this contest. I'm sure it will help in repairing those instruments I cannot fix by banging on the table.

This article was submitted by P.C. (name withheld by request) as part of Frankenstein's Fix, a design contest hosted by EE Times (US).